1. Field of the Invention
The present invention relates to hinge assemblies and, particularly, to a hinge assembly for foldable electronic devices, such as mobile telephones, electronic notebooks, and so on.
2. Discussion of the Related Art
With the development of wireless communication and information processing technologies, portable electronic devices such as mobile telephones and electronic notebooks are now in widespread use. These electronic devices enable consumers to enjoy the convenience of high technology services anytime and anywhere. Consumers particularly favor foldable electronic devices for their convenience.
Generally, foldable electronic devices have most of the electronics in one housing, called the body. The other housing, called the cover, normally contains fewer electronic components than the body. Other foldable electronic devices have all the electronics in the body, with the cover containing no electronics. Various types of hinge assemblies are used to join a body and a cover of a foldable electronic device, so that the cover can unfold up from and fold down upon the body. Manufacturers are constantly seeking to reduce the volume, size and/or weight of portable foldable electronic devices. Thus, it is desirable that the hinge assembly coupling the main housing with the cover is modularized and miniaturized. Modularized hinge assemblies usually consist of moving parts such as a cam member, a cam follower, a shaft, and a spring, held together in a unified structure. Where either the cam member or the cam follower directly contacts the spring. The structure is easily and quickly attached to the main housing and the cover during mass production. The cam member and the cam follower always contact each other under the force of the spring.
One kind of the hinge assembly includes a housing secured to a body of the mobile phone, a spring received in the housing, a rotary cam rod, and a shaft with a follower and a connecting portion. The rotary cam rod is received in the housing and engages with the housing. One end of the spring contacts an inner wall of the housing, and the other end of the spring resists one end of the rotary cam rod. The shaft passes through the rotary cam rod, the spring and a washer in that order.
Although the above-described hinge assembly is suitable for some foldable electronic devices, sliding friction is produced between the spring and the rotary cam rod because of relative rotation therebetween. This wastes energy and causes abrasion of the spring and the rotary cam rod. The abrasion may eventually lead to premature malfunction or failure of the hinge assembly.
What is needed, therefore, is a hinge assembly which has a relatively simple and small modularized configuration, which can be produced at low cost, and which has a relatively low amount of friction associated therewith.